The present invention relates to a monolithic or honey-comb type catalyst, in particular for purifying the exhaust gases of internal-combustion engines, composed of an inert ceramic or metallic substrate traversed by parallel flow channels, a support layer disposed thereon and composed of catalysis-promoting metal oxide and a catalytically active component supported by the metal oxide layer. The catalyst of the invention has improved start-up behavior.
An important characteristic of catalysts of the monolithic or honeycomb type is the speed with which the catalyst reaches the working temperature when exposed to a hot gas to be treated. The use of such catalysts as chemical catalysts or exhaust gas purifying catalysts, for example for industrial exhaust gases or engine exhaust gases, can be simplified substantially by improving this characteristic.
Hitherto an attempt has been made to achieve this by a more or less expensive increase in the amount of catalytically active material or by thermal insulation measures with respect to the catalyst unit.